Androidでツイートを取得して表示するコード

package com.example.parsejsonandroid;

import java.io.BufferedInputStream;
import java.io.BufferedReader;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.net.URL;
import java.net.URLConnection;
import java.util.ArrayList;
import java.util.List;

import org.json.JSONArray;
import org.json.JSONException;
import org.json.JSONObject;

import android.app.ListActivity;
import android.os.AsyncTask;
import android.os.Bundle;
import android.util.Log;
import android.view.Menu;
import android.widget.ArrayAdapter;

public class MainActivity extends ListActivity {
	URL url;
	URLConnection urlConnection;
	ArrayAdapter<String> arrayAdapter;
	List<String> tweetArray;
	StringBuilder builder;
	JSONArray jsonArray;
	GetTweet getTweet;

	@Override
	protected void onCreate(Bundle savedInstanceState) {
		super.onCreate(savedInstanceState);
		getTweet = new GetTweet();
		getTweet.execute();
	}

	class GetTweet extends AsyncTask<Void, Void, Void> {

		@Override
		protected void onPostExecute(Void result) {
			super.onPostExecute(result);
			arrayAdapter = new ArrayAdapter<String>(MainActivity.this,android.R.layout.simple_list_item_1,tweetArray);
			setListAdapter(arrayAdapter);
		}

		@Override
		protected Void doInBackground(Void... arg0) {
			try {
				url = new URL("https://api.twitter.com/1/statuses/user_timeline.json?screen_name=takapon_jp");
				urlConnection = url.openConnection();
				InputStream in = new BufferedInputStream(urlConnection.getInputStream());
				BufferedReader reader = new BufferedReader(new InputStreamReader(in, "UTF-8"));
				String line;
				builder = new StringBuilder();
				while ((line = reader.readLine()) != null) {
					builder.append(line);
				}
				in.close();
			} catch (Exception e) {
				e.printStackTrace();
			}
			tweetArray = new ArrayList<String>();
			try {
				jsonArray = new JSONArray(builder.toString());
				for (int i = 0; i < jsonArray.length(); i++) {
					JSONObject jsonObject = jsonArray.getJSONObject(i);
					tweetArray.add(jsonObject.getString("text"));
				}
			} catch (JSONException e) {
				e.printStackTrace();
			}
			return null;
		}
	}

	@Override
	public boolean onCreateOptionsMenu(Menu menu) {
		// Inflate the menu; this adds items to the action bar if it is present.
		getMenuInflater().inflate(R.menu.main, menu);
		return true;
	}

}